Nutrient Cycling in Bamboo Stands Ⅱ. Nutrient Input with Throughfall and Its Loss Through the Run-Off of the Watershed in Pure Phyllostachys pubescens Stands FERTILIZATION STUDIES IN BAMBOO STANDS WITH DIFFERENT END USES I.FOR BAMBOO TIMBER STAND An Evolution on Productiveness Factors of Phytlostachys pubescens Stand for Culms and Shoots by Quantitative Theory I